chem chem chem

1.Classify the following substances as acid or base according to Arrhenius
definition:
(a) H2SO4
(b) Ba(OH)2
(c) LiOH
(d) HF

2. Classify the following substances as acid or base according to Brønsted-Lowry
definition:
(a) NH3
(b) H2CO3
(c) K2CO3
(d) HNO3

3.Given that the Kb of ammonia (NH3) is 1.8 X 10 X 5 and Kb of dimethylamine
((CH3)2NH) is 5.9 X 10 X 4, which of them is a stronger base? Explain your
answer briefly based on the values of base dissociation constant (Kb).

4. For each of the following reactions:
(a) aluminium oxide + dilute sulphuric acid
(b) calcium hydroxide solution + dilute nitric acid
(i) Write a balanced chemical equation for the reaction.
(ii) Write a balanced ionic equation for the reaction.

5. What is the pH of 5.04 X 10-3 M HI? Is the solution neutral, acidic, or basic?

6. Citric acid (H3Cit) and sodium citrate (NaH2Cit) are common acidic buffer
system found in some food products such as jam. The main function of the buffer
system is to maintain a specific range of pH in food during processing or storage.
The working equation of such buffer system is as follows:
H3Cit^- (aq) <--- > H+(aq) + H2Cit^-(aq)
(a) Which chemical agent in the above equation is used to remove extra acid
added into the buffer? How does it work?
(b) Which chemical agent is used to remove extra base added into the buffer?
Explain briefly the working principle.

7. 5.32 g of sodium carbonate (Na2CO3) was dissolved in water and the solution was made up to 250.0 cm3 in a volumetric flask. Calculate the concentration of this standard solution expressed in:
(a) g dm3;
(b) molarity (M).
(Given: Molar mass of Na2CO3 = 106.0)